The present invention pertains generally to building and construction materials, and, more particularly, to foam building materials, such as expanded polystyrene (EPS) and extruded polystyrene (XPS) materials, and to methods and devices for imparting insect resistance, such as termite resistance, to such materials.
From the moment that a building or other structure is constructed, the building materials that form the structure are subject to attack from various environmental conditions. Weather, insects, fungi, and fire are continuous threats to the longevity, safety, and efficient operation of buildings. For example, insect infestation, such as infestation by termites, if uncontrolled, can cause severe damage to wood structure buildings.
Various methods have been employed to protect buildings and other structures from potential damage due to environmental and other conditions. A typical protective method involves treating the building materials from which the building or structure is built to resist attacks from various environmental and other conditions. For example, it is widely known that chromated copper arsenate (CCA) solutions may be used to treat wood building materials under high pressure. CCA treated wood is weather resistant, highly insect and fungi resistant, and, therefore, has a very long life. However, CCA treated wood is so highly insecticidal and fungicidal that it must be handled with considerable care. Recent evidence suggests that CCA treated wood may be harmful not only to insects and fungus, but also to humans and other animals that may come in contact with the CCA treated wood for prolonged periods of time.
As an alternative to CCA treatment, U.S. Pat. No. 6,387,300 to Bosserman describes a method for treating calcium borate ores to obtain useful boron compounds which may, in turn, be used to treat wood and other cellulose products such as plywood and oriented strand board (OSB). It is believed that such a calcium borate based wood treatment may be as effective as CCA as a wood preservative and protection against insect and fungus attack, without posing as significant a potential environmental hazard as CCA treated wood. Furthermore, the calcium borate solution used to treat wood is not water soluble, and thus leach resistant, thereby maintaining the protective properties of the wood treated with such a compound when exposed to various weather conditions such as rain or other precipitation.
In addition to wood, various other materials also commonly are used as building materials in the construction and related industries. For example, various foam products commonly are employed as building materials. Such foam products typically are made of a material such as polystyrene, or similar materials. Polystyrene building materials may be made using a variety of different conventional manufacturing processes, and include expanded polystyrene (EPS) and extruded polystyrene (XPS). Typical applications of such foam building materials include insulation for building foundations, walls, and roofing. Other foam applications include exterior building ornamentation and as a sub-grade displacement material. Sheets of foam building materials may be attached on site to building walls, foundations, etc., or may form the core of prefabricated insulated building panels (e.g., having a core of EPS or other foam material bonded to exterior skins of OSB, plywood, or similar materials). Foam may also be used to produce insulated concrete forms, which are used to provide a form for defining the structure of a poured concrete foundation or other structure and which are maintained in place to provide insulation to the foundation or other structure. Other applications of foam building materials also are known, and the various applications of foam materials in the building construction industry are likely to continue to grow.
Like wood products, foam building materials also are subject to attack from environmental and other conditions. In particular, foam insulation materials are subject to attack from various boring insects, such as termites. Foam insulation materials create a friendly environment for wood boring insects, such as carpenter ants and termites, which bore through the foam insulation to get at adjacent wooden structures. Insect boring through foam insulation reduces the insulating effectiveness of the insulation and, in severe cases, can cause building structural problems.
U.S. Pat. Nos. 5,194,323 and 5,270,108, both to Savoy, describe and illustrate an insulated building panel comprising a core of expanded polystyrene (EPS) foam bonded to at least two exterior skins of, e.g., oriented strand board (OSB). The panel is treated with an insecticidal and fungicidal chemical. The preferred chemical is a borate (salts or esters of boron). In particular, these patents describe the use of a sodium borate treatment chemical in the form of disodium octaborate tetrahydrate (Na2B8O134H2O). Several treatment methods are described, including immersion of the building panel in a solution of the treatment chemical and water, or spraying an aqueous solution of the treatment chemical on the building panel. The treatment process can be applied to the completed building panel or to the panel skins, to plain EPS, or to the building panel core separately. The EPS core may be treated by incorporating the sodium borate treatment chemical in either a dry powder or liquid form into the core during its formation.
Sodium borate treated foam building materials have been found to be resistant to insect and fungicidal attack. However, sodium borate is a water soluble compound. This can be advantageous, in that sodium borate may be mixed as a treatment chemical with water in an aqueous solution for easy application thereof to building materials. However, there is a corresponding limitation of sodium borate treated building materials. Since sodium borate is water soluble, it is important that building materials treated with sodium borate not be exposed to excess moisture or rain after treatment. Such exposure may cause the sodium borate to be leached or washed out from the treated building material, thereby removing the protective properties therefrom.
What is desired, therefore, is a foam building material that has long-term resistance to attack by termites and other insects. Such a foam building material should not pose any hazard to humans or to the environment either during installation thereof or anytime thereafter. Such an insect resistant foam building material also should be treated in such a manner that exposure to precipitation or other sources of moisture do not reduce the effectiveness of the foam building material to resist termites and other insects.
The present invention provides a foam material, e.g., a foam building material, which includes a calcium borate compound incorporated therein. A calcium borate infused foam material in accordance with the present invention is resistant to attack from termites and similar boring insects. Since calcium borate is a non-water soluble material, the protective properties of calcium borate infused foam materials will not leach out from or otherwise be removed from such insect resistant materials in accordance with the present invention when such materials are exposed to rain or other high moisture conditions. Thus, a calcium borate infused foam material in accordance with the present invention will maintain its insect resistance properties even after being exposed to rain or other high moisture conditions. Calcium borate does not present a health risk to humans, therefore, calcium borate infused foam materials in accordance with the present invention are environmentally friendly and can be handled and used without taking precautions other than those conventionally employed when installing or using untreated foam building materials.
In accordance with the present invention, calcium borate may be infused in any foam material having sufficient physical structure to be used for producing foam building materials, and the like. Polystyrene is a preferred foam material in which calcium borate may be infused in accordance with the present invention. In accordance with the present invention, calcium borate may be infused into expanded polystyrene (EPS) or extruded polystyrene (XPS) during the foam manufacturing process. A calcium borate compound in powdered form, e.g., finely ground colemanite ore, preferably may be employed during the EPS or XPS manufacturing process to provide a selected amount of calcium borate concentration in the resulting foam product. Preferably, a sufficient amount of calcium borate is infused into the foam material during the manufacturing process to impart insect resistant properties to the resulting foam material.
Calcium borate infused foam materials in accordance with the present invention may be molded, cut, or otherwise manufactured into any form for any application in which the insect resistant properties of the material would be useful. For example, a calcium borate infused foam material in accordance with the present invention may be molded, cut, extruded, or otherwise formed or combined with other materials to form various building materials such as sheets of foam insulation, insulated concrete forms, cores for insulated building panels, etc.
Further objects, features, and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings.